title: Selection for purine regulatory mutants in an E. coli hypoxanthine phosphoribosyl transferase-guanine phosphoribosyl transferase double mutant.
abstract: We have studied the relationship betwen purine salvage enzymes, 6-mercaptopurine resistance, and the purR phenotype in E. coli. Mutants resistant to 6-mercaptopurine were found to have defects in HPRT, the purR repressor, or in both. Analysis of these mutants led to the isolation of a hypoxanthine phosphoribosyl transferase-guanine phosphoribosyl transferase double mutant (hpt- gpt-) that is extremely sensitive to adenine. Two classes of adenine resistant mutants were isolated from this strain. The first class was deficient in APRT (apt-) while the second class represented purine regulatory mutants (purR-). There is thus selection for the purR phenotype in a hpt- gpt- background.
mesh_terms: D000225:Adenine / Q000494:pharmacology; D000228:Adenine Phosphoribosyltransferase / Q000235:genetics; D004926:Escherichia coli / Q000235:genetics*; D005809:Genes, Regulator; D007041:Hypoxanthine Phosphoribosyltransferase / Q000235:genetics*; D009154:Mutation; D010430:Pentosyltransferases / Q000235:genetics*; D011687:Purines / Q000378:metabolism*; D012641:Selection, Genetic
chemical_list: D011687:Purines; D010430:Pentosyltransferases; D000228:Adenine Phosphoribosyltransferase; D007041:Hypoxanthine Phosphoribosyltransferase; D000225:Adenine